Medical devices are used for drug delivery for various substances, such as morphine, Baclofen, Cisplatin, Clindamycin, Doxorubicin, Floxuridine (FUDR), Methotrexate, Heparin, Mitoxantrone, Octreotide Vinblastine, BDNF (brain derived nerve factor) etc. For example, conventional devices are specifically used to deliver morphine to cancer patients, baclofen to patients experiencing spasticity, and Floxuridine (FUDR) for to patients requiring chemotherapy (e.g., most of these are treatments already approved by the FDA).
However, conventional devices have a number of disadvantages. For example, conventional devices cannot optically measure the concentrations of the drug being delivered, nor can they optically measure or monitor the patient site to be treated or being treated to ensure that the patient receives the correct amount and concentration of the drug to be delivered or being delivered at that site. Conventional devices also do not provide for optical detection or an optical trigger signal and/or system to initiate drug delivery. Thus, conventional devices are not “smart” devices because they cannot measure biological signals and/or monitor and control the concentration and amount of drug delivery.
Further, since conventional devices do not monitor the concentration and quality of the delivered drug, they cannot provide this information to a microprocessor, and thus, the microprocessor cannot analyze or control the amount and/or concentration of the drug based on that information.
Conventional devices also cannot optically monitor the mixing of various substances that yield mixtures of short shelf life within these conventional devices, and thus cannot control the mixing of substances for optimum concentration of the mixed fluid to be delivered by the device to the patient.
Conventional devices can also experience corrosion due to the physical properties of substances to be delivered by these devices and the materials of conventional device components. Many of the drugs have high or low pHs that can cause severe corrosion to the components of conventional devices.
In addition, conventional devices do not have a coating suitable for a wide range of applications and delivery of various drugs (i.e., a “universal” coating), thereby leading to increased surgery to implant devices suitable for specific drugs or a limitation in the number of drugs that could be utilized in such devices.
In addition, conventional devices do not have coatings that can be easily converted into electrodes for the monitoring of electroactive analytes (e.g., organic molecules, dissolved gases, and metal ions) as well as the sensing of bioelectric events which indicate physiological function. Most conventional devices with electrodes require the utilization of separate structures with complicated interconnects (feedthroughs) welded or bonded to a substrate via harsh high temperature processes. Thus, there is a need for simpler fabrication procedures at lower temperatures for electrodes that allow three dimensional interconnection.
Further, conventional methods of manufacture of medical devices do not provide for methods of manufacture of devices having coatings useful for a wide variety of applications. For example, conventional methods of manufacture of medical devices do not provide for manufacture of coatings having optical windows for optical sensors, or selectively doped coatings to provide for monitoring of electrochemical conditions in various locations throughout the device surface, or coatings to provide corrosion resistance.
While optical sensors have been used in implantable devices to monitor oxygen in hemoglobin, optical sensors have not been used in implantable devices to monitor and control drug delivery in medical devices. Further, the optical sensors that have been used to monitor oxygen in hemoglobin comprise sapphire windows brazed onto optical sensors. Such brazing requires high temperature manual fabrication and is not well suited for microfabrication and automated manufacture.
Catheters having optical sensors could be used on a temporary basis to measure the amount of certain substances, such as nitrous oxide, in connection with temporary drug delivery. They have been used as oximeters as described in U.S. Pat. No. 4,750,495. However, conventional medical devices which are implantable are not capable of or designed to measure a large variety of concentrations or chemical conditions via optical and electrochemical sensors, and thus cannot control treatment, such as drug delivery, to a patient.
Thus, there is a great need for medical devices that overcome the above deficiencies in conventional medical devices and the methods of manufacture thereof.